1. Field of Invention
This invention relates to a stage device and an exposure apparatus, and to a method of manufacturing a device, and more specifically to a stage device that drives a stage on which an object is mounted, an exposure apparatus provided with the stage device as, for example, a driving device of a substrate, and to a method of manufacturing a device using the exposure apparatus.
2. Description of Related Art
Conventionally, in a lithographic process to manufacture a semiconductor element, a liquid crystal display element, or the like, an exposure apparatus has been used that transfers a pattern formed on a mask or a reticle (hereafter referred to as xe2x80x9creticlexe2x80x9d) onto a substrate (hereafter referred to as xe2x80x9cwaferxe2x80x9d) such as a glass plate or a wafer, where a resist or the like is coated, through a projection optical system.
In this type of exposure apparatus, in order to position a wafer at an exposure position with high accuracy, a stage device has been used to control a position and a posture in six degrees-of-freedom, such as X, Y, Z, xcex8X, xcex8Y,xcex8Z,of a wafer holder that holds the wafer. It is common in this type of stage device to drive an XY stage in the two-dimensional X-Y direction by a Y-axis driving linear motor and a pair of X-axis driving linear motors. In addition, a xcex8Z table mounted on the X-Y stage, and a three degrees-of-freedom driving table (Z leveling table), mounted on the xcex8Z table, drive a wafer holder that holds a wafer in three degrees-of-freedom directions such as Z, xcex8X,and xcex8Y.
In general, the XY stage moves on a holding plate (a stage base) having a smooth reference surface. Additionally, the XY stage is non-contactingly supported over the reference surface by a non-contact bearing, for example, an air bearing, arranged at the bottom of the XY stage with a clearance of several xcexcm. Therefore, a posture of the XY stage with respect to the reference surface can be constantly maintained, and a long life expectancy can be expected by avoiding the effects of mechanical friction.
Meanwhile, in a conventional exposure apparatus, when an exposure operation for a wafer mounted on an XY stage is completed, wafer replacement and alignment (search alignment, fine alignment) are performed, then exposure is performed, and then wafer replacement is again performed. Thus, three significant operations, such as: (1) wafer replacement; (2) alignment; (3) exposure; and (4) wafer replacement, or the like, are repeated. Because of this, time (hereafter referred to as xe2x80x9coverhead timexe2x80x9d) for wafer replacement and alignment causes deterioration of throughput. Therefore, many xe2x80x9cplurality of stagesxe2x80x9d arrangements have been suggested in which a plurality of stages are prepared, wafer replacement and alignment are performed on a separate stage during wafer exposure on one stage, and throughput is improved by such simultaneous parallel processing (e.g., see Japanese Laid-Open Patent Application No. 8-51069 and WO98/24115).
In an exposure apparatus with a plurality of stages as described above, compared to a single-stage type exposure apparatus, a stage moving area is naturally enlarged. Therefore, a reference surface used during stage movement, and as a result, a holding plate on which the reference surface is formed, needs to be enlarged (making its area large). The holding plate, particularly the reference surface, becomes a reference during stage movement. Thus, extremely high accuracy processing for the surface is required in order to suitably maintain stage stability and position controllability. However, it is extremely difficult to fabricate a large holding plate with a high surface accuracy. In addition, the cost increases as the reference surface area increases. Furthermore, as the holding plate becomes enlarged, it is difficult to support the holding plate without affecting the reference surface by warping due to its own weight. As a result, this deteriorates controllability of the position of the stage.
These shortcomings are not limited to a plurality of stages, but apply to an exposure apparatus with a single stage as well. In addition, in future exposure apparatus, as a wavelength for exposure is shortened, there is a high possibility of using a catadioptric system as a projection optical system. A diameter of a bottom part of this catadioptric system is large, so a distance between an exposure part and an alignment part or a wafer replacement part naturally becomes long. Furthermore, this is not limited to a catadioptric system, but even in a dioptric system, when a diameter of a projection optical system is enlarged in order to improve a numerical aperture, in the same manner, a distance between an exposure part and an alignment part or a wafer replacement part naturally becomes long. This causes enlargement of the holding plate due to an area increase in a range where the stage moves. In addition to this, the time between wafer replacement alignment and exposure naturally takes long, so this causes deterioration of throughput. Therefore, one problem to be solved is how this time can be shortened in order to improve throughput.
Additionally, when an exposure operation that improves throughput, an alignment operation, and a substrate replacement operation are simultaneously performed in a parallel manner by a plurality of stages, vibration due to driving one stage is transmitted to the other stages via the holding plate, so controlling the position of each stage deteriorates.
This invention is made in consideration of the above-mentioned circumstances. One object of the invention is to provide a stage device that can suitably maintain control of the position of the stage.
Another object of this invention is to provide an exposure apparatus that improves exposure accuracy with respect to a substrate on a stage and simultaneously improves throughput.
A further object of this invention is to provide a method of manufacturing a device with improved productivity, resulting in a device having a high level of integration.
A stage device according to one aspect of the invention is provided with a movable stage that holds an object. A first reference member on which a first movement reference surface is formed, is used as a reference when the stage moves. A second reference member on which a second movement reference surface, different from the first movement reference surface, is formed is provided. In addition, a switching device switches between a first state in which the stage is movable along the first movement reference surface, and a second state in which the stage is movable along the second movement reference surface.
According to this aspect of the invention, the switching device switches between a first state in which the stage is movable along the first movement reference surface and a second state in which the stage is movable along the second movement reference surface. Because of this, there is no inconvenience for stage movement even if the first reference member on which the first movement reference surface is formed is arranged physically separated from the second reference member on which the second movement reference surface is formed. Compared to the case on which the first movement reference surface and the second movement reference surface are formed on the same reference member, an area of the reference surface of the respective reference members can be made smaller. Therefore, for example, even if holding plates are used as the first reference member and as the second reference member, the respective reference surfaces can be processed with high accuracy. Thus, processing difficulty of the reference surfaces can be overcome. At the same time, stage stability can be ensured during movement in which the first and second reference surfaces are used as references, and positional controllability of the stage can be maintained.
In this case, the first and second reference members can be similar types of members, or can be constituted by different types of members. In the latter case, for example, the first reference member can be a holding plate, and the second reference member can be a pair of guides. In this case, compared to the case where the first and second reference members are holding plates, the entire stage device can be made more light-weight. Furthermore, for example, when highly accurate positional controllability (including stability) of the stage is required in a specified region and highly accurate positional controllability of the stage is not required outside the specified region, the first reference member on which the first movement reference surface is formed is located in the specified region and is constituted by a holding plate, and the second reference member on which the second movement reference surface is formed is located outside the specified region, and is constituted by the pair of guides. Therefore, the holding plate can be made smaller, and its processing can be simplified. Furthermore, the required accuracy of positional controllability of the stage can be obtained.
stage device according to another aspect of the invention includes a first stage and a second stage. The first stage moves within a first region that includes a specified region. The second stage moves within a second region that also includes the specified region. A first reference member includes a first movement reference surface that is located in the specified region. In addition, at least one second reference member is provided, and includes a second movement reference surface located outside the specified region. The second movement reference surface is used as a reference by a specified stage, which is at least one stage among the first and second stages. A switching device is provided to switch between a first state in which the specified stage can move within the specified region, and a second state in which the specified stage can move outside of the specified region.
Here, xe2x80x9cat least one second reference member on which a second movement reference surface outside the specified regionxe2x80x9d refers to the following context, respectively, depending on whether the specified stage is one or both of the first and second stages and whether one or a plurality of second reference members are provided. (a) If the specified stage is one of the first and second stages, the second movement reference surface outside the specified region is formed on the second reference member, and a third movement reference surface outside the specified region is provided for the other stage. (b) If the specified stage refers to both the first and second stages, the second movement reference surface outside the specified region is formed on the second reference member for use by both stages. (c) In the case of a plurality of second reference members when the specified stage refers to both the first and second stages, the second movement reference surface outside the specified region can be formed on different second reference members.
According to this aspect of the invention, there is provided a first reference member on which a first movement reference surface in a specified region of the first and second stages is formed and at least one second reference member on which a second movement reference surface outside the specified region of a specified stage, which is at least one stage among the first and second stages. Additionally, a switching device switches between a first state in which the specified stage can move in the specified region along the first movement reference surface of the first reference member, and a second state in which the specified stage can move outside of the specified region along the second movement reference surface of the second reference member. Because of this, even if the first reference member on which the first movement reference surface in the specified region is formed is arranged physically separate from the second reference member on which the second movement reference surface outside the specified region is formed, there is no inconvenience for movement of the specified stage, which is at least one stage among the first and second stages, in the specified region and outside of the specified region. Therefore, compared to the case when the first movement reference surface of the specified region and the second movement reference surface outside of the specified region of the first and second stages are formed on the same reference member, an area of the respective reference members can be made smaller. In particular, when the specified stage is both the first and second stages and there are two second reference members, an area of the first movement reference surface in the specified region, that is, the first reference member, can be minimized.
Therefore, for example, even if a holding plate is used as the first and second reference members, the respective movement reference surfaces can be processed with high accuracy. Accordingly, processing difficulty of the movement reference surfaces can be overcome, stability of the respective stages can be ensured during movement when the first and second reference members are used as references, and the positional controllability of the stages can be suitably maintained.
In this case, a single second reference member in addition to the first reference member can also be used for both stages. However, it is preferable that two second reference members are separately arranged corresponding to the respective first and second stages. In this case, as described earlier, an area of the first movement reference surface of the first reference member can be minimized. At the same time, second reference members are separately arranged corresponding to the respective stages, so when the first and second states of the first and second stages are respectively switched by a switching device, it is possible for both stages to avoid the use of one reference member simultaneously. Therefore, vibration due to movement of one stage is not transmitted to the other stage via a reference member, and positional controllability of the respective stages can be improved.
The first and second reference members can be constituted by the same type of members, but can also be constituted by different types of members. In the latter case, for example, the first reference member can be a holding plate, and the second reference member can be a pair of guides. In this case, compared to the case when the first and second reference members are holding plates, the entire stage device can be made more light-weight. Furthermore, for example, when highly accurate positional controllability (including stability) of a stage in the specified region is required and highly accurate positional controllability is not as important outside of the specified region, the first reference member on which the first movement reference surface in the specified region of both stages is formed can be constituted by a highly accurate and precisely processed holding plate, and the second reference member on which the second movement reference surface outside the specified region of at least one stage is formed can be constituted by a pair of guides that do not need to be processed with as high a degree of accuracy as the holding plate. Therefore, the holding plate can be made smaller, enabling its processing to be simplified, and the required accuracy of positional controllability of the stage can be satisfied.
The switching device can include actuators the relatively move the first and second reference members in a direction perpendicular to the first and second movement reference surfaces, and drivers that drive the specified stage along the first movement reference surface. In this case, even if a positional relationship between the first movement reference surface in the specified region and the second movement reference surface outside the specified region formed on the second reference member is shifted from a desired positional relationship in a direction (hereafter referred to as xe2x80x9cnormal line directionxe2x80x9d) perpendicular to the first and second movement reference surfaces, by relatively moving the first and second reference members in the normal line direction by the actuators, they can be adjusted to the desired positional relationship. After this adjustment, by driving the specified stage along the first and second movement reference surfaces between the specified region and the region outside of the specified region by the driver, the specified stage can be switched between the first and second states.
Here, the actuators can drive either the first or second reference members in the normal line direction or can relatively drive both the first and second reference members in the normal line direction.
The actuators can include at least one of a mechanical actuator, an electromagnetic actuator, an actuator that converts electrical power to mechanical power, and an actuator using a vacuum.
The switching device can switch between a first support state that supports the specified stage over the first reference member due to a balance of a vacuum preload force and a hydrostatic pressure of pressurized gas between the specified stage and the first reference member, and a second support state that supports the specified stage over the second reference member due to a balance of a vacuum preload force and a hydrostatic pressure of pressurized gas between the specified stage and the second reference member.
In this case, the switching device, as the specified stage is switched between the first and second states, mutually switches from the first support state to the second support state of the specified stage. Because of this, in the case of completely different areas of the first movement reference surface on the first reference member and the second movement reference surface on the second reference member, pressurized gas corresponding to the areas of the respective movement reference surfaces is emitted, so an appropriate emission state of pressurized gas corresponding to the respective support states can be accomplished. Because of this, wasteful emission of pressurized gas can be prevented. Furthermore, in this case, a relative position in the normal line direction of at least one of the first and second reference members and the specified stage can be adjusted by adjusting the balance in at least one of the first and second support states of the specified stage. As a result, the relative position in a normal line direction of the first and second reference members can be substantially adjusted by adjusting the balance in at least one of the first and second support states of the specified stage.
The driver can include first actuators that drive the specified stage in the specified region and second actuators that drive the specified stage outside the specified region. Therefore, for example, when one stage is the specified stage, it is possible to prevent vibration that occurs when the specified stage moves using the second movement reference surface on the second reference member as a reference from being transmitted via that reference member to the other stage which moves using the first movement reference surface formed on the first reference member as a reference. In addition, it is also possible to prevent vibration from being transmitted to the other stage via the driver. Therefore, positional controllability of the stages can also be further improved.
A stage device according to another aspect of the invention includes a first stage that moves within a first region that includes a specified region, and a second stage that moves within a second region that also includes the specified region. In addition, a stage base is provided, and includes a first movement reference surface that is used as a reference when the first and second stages move in the specified region, and second and third movement reference surfaces that are positioned on opposite sides of the first movement reference surface in the moving directions of the first and second stages and that are used as references when the first and second stages respectively move outside the specified region. A surface accuracy of the second and third movement reference surfaces is rougher than a surface accuracy of the first movement reference surface.
According to this aspect of the invention, when highly accurate positional controllability (including stability) of the stages is required when moving in the specified region, and highly accurate positional controllability (including stability) of the stages is not required when moving outside the specified region, the positional controllability of both stages that is required inside the specified region and outside the specified region can be maintained. In this case, it suffices to increase only the surface accuracy of the first movement reference surface among the first, second, and third movement reference surfaces formed on the stage base. Therefore, even if movement reference surfaces that are used as references when the first and second stages are moved are formed on one stage base, a reference surface of the stage base can be easily processed.
In this aspect of the invention, a clearance changing device may be further provided that changes a clearance between the first movement reference surface and the first and second stages when the first and second stages move in the specified region, and a clearance between the second and third movement reference surfaces and the first and second stages when the first and second stages move outside the specified region. In this case, when the respective stages move by using the first movement reference surface, which has high surface accuracy, as a reference, the clearance changing device improves positional controllability by making the clearance between the stage and the movement reference surface small. When the respective stages move by using the second or third movement reference surfaces, which have a lower surface accuracy, as a reference, the clearance changing device makes the clearance between the stage and the movement reference surface larger. Thus, the stage can be prevented from contacting a movement reference surface with low surface accuracy.
It is also possible to provide first and second actuators that respectively drive the first and second stages along the first movement reference surface, and third and fourth actuators that are arranged independently from the first and second actuators, and respectively drive the first and second stages along the second and third reference surfaces. In this case, vibration that occurs when one stage moves is not transmitted to the other stage via the actuators, so positional controllability of both stages can be further improved.
The first and third actuators may be linear motors having (i.e., sharing) a common movable part, and having mutually different stationary parts. The second and fourth actuators may be linear motors having a common movable part and having mutually different stationary parts, and the first and second actuators may have a common stationary part. In this case, the first stage is driven by the first and third actuators, and the second stage is driven by the second and fourth actuators. Additionally, the movable part that drives the respective stages is common, and the stationary part that drives both stages in the specified region is common. Therefore, even though the stage device has four pairs of actuators, it is only necessary to provide three pairs of stationary parts and two pairs of movable parts. Therefore, the entire stage device can be made lighter in weight. Furthermore, for example, if both stages are not simultaneously located in the specified region, vibration of one stage is not transmitted to the other stage via the actuators, so positional controllability of the respective stages can also be improved.
Another aspect of the invention relates to an exposure apparatus that exposes substrates with an energy beam and transfers a predetermined pattern onto the substrates. Such an exposure apparatus includes the stage device according to any of the aspects of the invention mentioned above. The stage device can be used to hold the substrates, for example.
The positional controllability of the respective stages can be suitability maintained whether they are located in the specified region or outside of the specified region, depending on the required accuracy. Furthermore, exposure is performed for the substrates on the first and second stages when located in the specified region, and at least one of substrate alignment and substrate replacement is performed on the first and second stages when located outside of the specified region, so simultaneous parallel processing of the two stages can be performed. Therefore, exposure accuracy and throughput can be simultaneously improved.
In this case, the first and second stages may be provided with moving tables on which the substrates are respectively mounted and moving guides that drive the moving tables in a first direction and can be moved in a second direction perpendicular to the first direction. The first and second stages may be further provided with a controller that causes the one moving table on which the substrate alignment is completed to wait in the vicinity of the position in which the exposure is performed during the performance of substrate exposure on the other moving table. In this case, the respective stages are provided with moving tables on which substrates are mounted and moving guides that drive the moving tables in a first direction and can be moved in a second direction perpendicular to the first direction. Therefore, the respective moving tables (and substrates) can be moved in a two-dimensional direction. Furthermore, by providing a controller that causes one moving table on which substrate alignment is completed to wait in the vicinity of the position at which the exposure is performed during the substrate exposure on the other moving table, the exposure operation of the substrate on the other stage can begin immediately after exposure of the one stage is completed, and throughput can be further improved. Additionally, even when the distance between the exposure position and the alignment position becomes long, deterioration of throughput can be controlled.
Another aspect of the invention relates to a method of manufacturing a device including a lithography process that performs exposure using the exposure apparatus described above.
According to this aspect of the invention, productivity of manufacturing devices having a high degree of integration can be improved due to improvement of exposure accuracy and throughput.